First of all, thank you for looking at the report. The report is sent by the plug-in itself, I think it is sufficiently accurate. I have already done the test you suggest and even if the crawler indicates the page with a HIT, I connect (immediately) and find MISS. As a browser it works, because when I refresh the page I find a HIT.
Regarding the error message you have identified, I can tell you that the domain the crawlers browse is not actually set to DNS but set at system level as an IP-domain association in the host file of the server (CentoOS 8) and of the operating system my client is running on (Windows 10).
Can you please explain to me what it refers to? How does the crawler cache a page if it cannot reach it due to the problem in the DNS?
Thanks again, Paolo.